Automatic wafer centering method and apparatus

ABSTRACT

A substrate transport apparatus including a transport chamber, a drive section, a robot arm having an end effector at a distal end configured to support a substrate and being connected to the drive section generating at least arm motion in a radial direction extending and retracting the arm, an imaging system with a camera mounted in a predetermined location to image at least part of the robot arm, and a controller connected to the imaging system to image the arm moving to a predetermined repeatable position, the controller effecting capture of a first image of the robot arm proximate to the repeatable position decoupled from encoder data of the drive axis, wherein the controller calculates a positional variance of the robot arm from comparison of the first image with a calibration image, and from the positional variance determines a motion compensation factor changing the extended position of the robot arm.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of, and claims the benefit of,U.S. Provisional Patent Application No. 62/623,843 filed on Jan. 30,2018, the disclosure of which is incorporated herein by reference in itsentirety.

BACKGROUND 1. Field

The exemplary embodiments generally relate to substrate processingapparatus, and more particularly, to substrate transport apparatus.

2. Brief Description of Related Developments

A substrate transport robot within a transfer chamber moves substratesamong different process modules where different operations, such asetching, coating, etc. are performed. Production processes used by, forexample, semiconductor device manufacturers and materials producersoften require precise positioning of substrates in the substrateprocessing equipment. Accurate placement of the substrates may behindered by various factors, such as, e.g., thermal effects. Forexample, thermal expansion and contraction of the substrate transportrobot may shift a position of the substrate from the desired positionvia, e.g., thermal expansion or contraction of the robot components.

A processing system that does not take into account these variousfactors that affect the transport robot may be inundated with inaccurateplacement of the substrates.

Several methods and apparatus have been utilized to provide positioncompensation for substrates and various components of the substratetransport robot. In one approach, optical sensors are disposed in, e.g.,the transfer chamber. When the transport robot or substrate passes bythe optical sensor, the system can determine the position of thesubstrate with respect to the end effector of the transport robot using,e.g., encoder data on the motor of the transport robot. Based on thedetected position, the system can correct for substrate position errors.The process of determining the position based on encoder data isdifficult and cumbersome and may slow down processing time.

As semiconductor device dimensions have decreased, increased handlingaccuracy is desirable, thus it would be advantageous to provide asubstrate processing apparatus providing increased accuracy withposition compensation independent of encoder data.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and other features of the disclosed embodiment areexplained in the following description, taken in connection with theaccompanying drawings, wherein:

FIGS. 1A-1D are schematic illustrations of substrate processingapparatus in accordance with aspects of the disclosed embodiment;

FIGS. 1E and 1F are schematic illustrations of portions of the substrateprocessing apparatus of FIGS. 1A-1D in accordance with aspects of thedisclosed embodiment;

FIGS. 2A-2D are schematic illustrations of a substrate transportapparatus in accordance with aspects of the disclosed embodiment;

FIG. 2E is a schematic illustration of a drive section in accordancewith aspects of the disclosed embodiment;

FIGS. 2F-2J are schematic illustrations of transport arms in accordancewith aspects of the disclosed embodiment;

FIG. 2K is a schematic illustration of a drive section in accordancewith aspects of the disclosed embodiment;

FIGS. 3A-3E are schematic illustrations of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIGS. 3F and 3G are schematic illustrations of a drive section inaccordance with aspects of the disclosed embodiment;

FIGS. 4A-4B are schematic illustrations of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 5 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 6 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 7 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 8 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 9 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 10 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 11 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 12 is a schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 13 is schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 14 is schematic illustration of a portion of the substratetransport apparatus illustrated in FIGS. 2A-2D in accordance withaspects of the disclosed embodiment;

FIG. 15 is an exemplary graph illustrating use of one or more aspects ofthe disclosed embodiment compared to conventional methods;

FIG. 16 is a flow chart of a method of operation of a substratetransport apparatus in accordance with one or more aspects of thedisclosed embodiment; and

FIG. 17 is a flow chart of a method of operation of a substratetransport apparatus in accordance with one or more aspects of thedisclosed embodiment.

DETAILED DESCRIPTION

FIGS. 1A-1D and 5 are schematic illustrations of substrate processingapparatus in accordance with aspects of the disclosed embodiment.Although the aspects of the disclosed embodiment will be described withreference to the drawings, it should be understood that the aspects ofthe disclosed embodiment can be embodied in many forms. In addition, anysuitable size, shape or type of elements or materials could be used.

As will be described in greater detail below, the aspects of thedisclosed embodiment provide for a substrate transport apparatus 125A-D(FIGS. 1A-1D), 510 (FIG. 5) including an imaging system 500 (FIG. 5) forcorrecting positional errors of at least one robot arm 210, 210A, 211,211A, 212, 213, 214, 215, 216, 217, 218 of, due to, e.g., thermaleffects (expansion/contraction) of the at least one robot arm 210, 210A,211, 211A, 212, 213, 214, 215, 216, 217, 218. In the aspects of thedisclosed embodiment, a camera 501 (FIGS. 8-9) of the imaging system 500captures a first image 570 (FIG. 10) of at least part 580 (FIG. 6) ofthe robot arm 210, 210A, 211, 211A, 212, 213, 214, 215, 216, 217, 218positioned in a predetermined repeatable location 650, 650′ (FIG. 6) andcompares the first image 570 with a calibration image 590 (FIG. 10)stored in, for example, a controller 110 to determine any positionalvariances Δ_(PV) (FIG. 10) between the first image 570 and thecalibration image 590. For example, the robot arm 210A, 211A (or any ofthe other robot arms described herein) of the substrate transportapparatus 125A-D, 510 is factory set or ‘zeroed’ at the predeterminedrepeatable position 650, 650′ so that the robot arm 210A, 211A mayconsistently return to the ‘zeroed’ position for determination of theposition variances Δ_(PV) as will be further described herein.

The substrate processing apparatus 100A, 100B, 100C, 100D, such as forexample a semiconductor tool station, is shown in accordance with anaspect of the disclosed embodiment. Although a semiconductor toolstation is shown in the drawings, the aspects of the disclosedembodiment described herein can be applied to any tool station orapplication employing robotic manipulators. In one aspect the processingapparatus 100A, 100B, 100C, 100D are shown as having cluster toolarrangements (e.g. having substrate holding stations connected to acentral chamber) while in other aspects the processing apparatus may bea linearly arranged tool, however the aspects of the disclosedembodiment may be applied to any suitable tool station. The apparatus100A, 100B, 100C, 100D generally include an atmospheric front end 101,at least one vacuum load lock 102, 102A, 102B and a vacuum back end 103.The at least one vacuum load lock 102, 102A, 102B may be coupled to anysuitable port(s) or opening(s) of the front end 101 and/or back end 103in any suitable arrangement. For example, in one aspect the one or moreload locks 102, 102A, 102B may be arranged in a common horizontal planein a side by side arrangement as can be seen in FIGS. 1B-1C. In otheraspects the one or more load locks may be arranged in a grid format suchthat at least two load locks 102A, 102B, 102C, 102D are arranged in rows(e.g. having spaced apart horizontal planes) and columns (e.g. havingspaced apart vertical planes) as shown in FIG. 1E. In still otheraspects the one or more load lock may be a single in-line load lock 102as shown in FIG. 1A. In yet another aspect the at least one load lock102, 102E may be arranged in a stacked in-line arrangement as shown inFIG. 1F. It should be understood that while the load locks areillustrated on end 100E1 or facet 100F1 of a transport chamber 125A,125B, 125C, 125D in other aspects the one or more load lock may bearranged on any number of sides 100S1, 100S2, ends 100E1, 100E2 orfacets 100F1-100F8 of the transport chamber 125A, 125B, 125C, 125D. Eachof the at least one load lock may also include one or morewafer/substrate resting planes WRP (FIG. 1F) in which substrates areheld on suitable supports within the respective load lock. In otheraspects, the tool station may have any suitable configuration. Thecomponents of each of the front end 101, the at least one load lock 102,102A, 102B and back end 103 may be connected to a controller 110 whichmay be part of any suitable control architecture such as, for example, aclustered architecture control. The control system may be a closed loopcontroller having a master controller, cluster controllers andautonomous remote controllers such as those disclosed in U.S. Pat. No.7,904,182 entitled “Scalable Motion Control System” issued on Mar. 8,2011 the disclosure of which is incorporated herein by reference in itsentirety. In other aspects, any suitable controller and/or controlsystem may be utilized.

In one aspect, the front end 101 generally includes load port modules105 and a mini-environment 106 such as for example an equipment frontend module (EFEM). The load port modules 105 may be box opener/loader totool standard (BOLTS) interfaces that conform to SEMI standards E15.1,E47.1, E62, E19.5 or E1.9 for 300 mm load ports, front opening or bottomopening boxes/pods and cassettes. In other aspects, the load portmodules may be configured as 200 mm wafer/substrate interfaces, 450 mmwafer/substrate interfaces or any other suitable substrate interfacessuch as for example larger or smaller semiconductor wafers/substrates,flat panels for flat panel displays, solar panels, reticles or any othersuitable object. Although three load port modules 105 are shown in FIGS.1A-1D, in other aspects any suitable number of load port modules may beincorporated into the front end 101. The load port modules 105 may beconfigured to receive substrate carriers or cassettes C from an overheadtransport system, automatic guided vehicles, person guided vehicles,rail guided vehicles or from any other suitable transport method. Theload port modules 105 may interface with the mini-environment 106through load ports 107. The load ports 107 may allow the passage ofsubstrates between the substrate cassettes and the mini-environment 106.The mini-environment 106 generally includes any suitable transfer robot108 which may incorporate one or more aspects of the disclosedembodiment described herein. In one aspect the robot 108 may be a trackmounted robot such as that described in, for example, U.S. Pat. No.6,002,840 issued on Dec. 14, 1999; U.S. Pat. No. 8,419,341 issued Apr.16, 2013; and U.S. Pat. No. 7,648,327 issued on Jan. 19, 2010, thedisclosures of which are incorporated by reference herein in theirentireties. In other aspects the robot 108 may be substantially similarto that described herein with respect to the back end 103. Themini-environment 106 may provide a controlled, clean zone for substratetransfer between multiple load port modules.

The at least one vacuum load lock 102, 102A, 102B may be located betweenand connected to the mini-environment 106 and the back end 103. In otheraspects the load ports 105 may be coupled substantially directly to theat least one load lock 102, 102A, 102B or the transport chamber 125A,125B, 125C, 125D where the substrate carrier C is pumped down to avacuum of the transport chamber 125A, 125B, 125C, 125D and substratesare transferred directly between the substrate carrier C and the loadlock or transfer chamber. In this aspect, the substrate carrier C mayfunction as a load lock such that a processing vacuum of the transportchamber extends into the substrate carrier C. As may be realized, wherethe substrate carrier C is coupled substantially directly to the loadlock through a suitable load port any suitable transfer apparatus may beprovided within the load lock or otherwise have access to the carrier Cfor transferring substrates to and from the substrate carrier C. It isnoted that the term vacuum as used herein may denote a high vacuum suchas 10-5 Torr or below in which the substrates are processed. The atleast one load lock 102, 102A, 102B generally includes atmospheric andvacuum slot valves. The slot valves of the load locks 102, 102A, 102B(as well as for the substrate station modules 130) may provide theenvironmental isolation employed to evacuate the load lock after loadinga substrate from the atmospheric front end and to maintain the vacuum inthe transport chamber when venting the lock with an inert gas such asnitrogen. As will be described herein, the slot valves of the processingapparatus 100A, 100B, 100C, 100D may be located in the same plane,different vertically stacked planes or a combination of slot valveslocated in the same plane and slot valves located in differentvertically stacked planes (as described above with respect to the loadports) to accommodate transfer of substrates to and from at least thesubstrate station modules 130 and load locks 102, 102A, 102B coupled tothe transport chamber 125A, 125B, 125C, 125D. The at least one load lock102, 102A, 102B (and/or the front end 101) may also include an alignerfor aligning a fiducial of the substrate to a desired position forprocessing or any other suitable substrate metrology equipment. In otheraspects, the vacuum load lock may be located in any suitable location ofthe processing apparatus and have any suitable configuration.

The vacuum back end 103 generally includes a transport chamber 125A,125B, 125C, 125D, one or more substrate station modules 130 and anysuitable number of substrate transfer robots 104 that includes one ormore transfer robots and may include one or more aspects of thedisclosed embodiments described herein. The transport chamber 125A,125B, 125C, 125D may have any suitable shape and size that, for example,complies with SEMI standard E72 guidelines. The substrate transfer robot104 and the one or more transfer robot will be described below and maybe located at least partly within the transport chamber 125A, 125B,125C, 125D to transport substrates between the load lock 102, 102A, 102B(or between a cassette C located at a load port) and the varioussubstrate station modules 130. In one aspect the substrate transferrobot 104 may be removable from the transport chamber 125A, 125B, 125C,125D as a modular unit such that the substrate transfer robot 104complies with SEMI standard E72 guidelines.

The substrate station modules 130 may operate on the substrates throughvarious deposition, etching, or other types of processes to formelectrical circuitry or other desired structure on the substrates.Typical processes include but are not limited to thin film processesthat use a vacuum such as plasma etch or other etching processes,chemical vapor deposition (CVD), plasma vapor deposition (PVD),implantation such as ion implantation, metrology, rapid thermalprocessing (RTP), dry strip atomic layer deposition (ALD),oxidation/diffusion, forming of nitrides, vacuum lithography, epitaxy(EPI), wire bonder and evaporation or other thin film processes that usevacuum pressures. The substrate station modules 130 are communicablyconnected to the transport chamber 125A, 125B, 125C, 125D in anysuitable manner, such as through slot valves SV, to allow substrates tobe passed from the transport chamber 125 to the substrate stationmodules 130 and vice versa. The slot valves SV of the transport chamber125 may be arranged to allow for the connection of twin (e.g. more thanone substrate processing chamber located within a common housing) orside-by-side substrate station modules 130T1, 130T2, single substratestation modules 130S and/or stacked process modules/load locks (FIGS. 1Eand 1F).

It is noted that the transfer of substrates to and from the substratestation modules 130, load locks 102, 102A, 102B (or cassette C) coupledto the transfer chamber 125A, 125B, 125C, 125D may occur when one ormore arms of the substrate transfer robot 104 are aligned with apredetermined substrate station module 130. In accordance with aspectsof the disclosed embodiment one or more substrates may be transferred toa respective predetermined substrate station module 130 individually orsubstantially simultaneously (e.g. such as when substrates arepicked/placed from side-by-side or tandem processing stations as shownin FIGS. 1B, 1C and 1D. In one aspect the substrate transfer robot 104may be mounted on a boom arm 143 (see e.g. FIG. 1D) or linear carriage144 such as that described in U.S. provisional patent application No.61/892,849 entitled “Processing Apparatus” and filed on Oct. 18, 2013and 61/904,908 entitled “Processing Apparatus” and filed on Nov. 15,2013 and International patent application number PCT/US13/25513 entitled“Substrate Processing Apparatus” and filed on Feb. 11, 2013, thedisclosures of which are incorporated herein by reference in theirentireties.

Referring now to FIGS. 2A-2D, in one aspect the substrate transfer robot104 includes at least one drive section 200, 201 and at least one robotarm 210, 211, 212, 213. It is noted that the substrate transfer robot104 illustrated is exemplary and in other aspects may have any suitableconfiguration substantially similar to that described in U.S.application Ser. No. 14/568,742 entitled “Substrate transport apparatus”and filed on Dec. 12, 2014, the disclosure of which is incorporated byreference herein in its entirety. The at least one drive section 200,201 may include a common drive section 200 that includes a frame 200Fthat houses one or more of a Z axis drive 270 and a rotational drivesection 282. An interior 200FI of the frame 200F may be sealed in anysuitable manner as will be described below. In one aspect the Z axisdrive may be any suitable drive configured to move the at least onerobot arm 210, 211, 212, 213 along the Z axis. The Z axis drive isillustrated in FIG. 2E as a screw type drive but in other aspects thedrive may be any suitable linear drive such as a linear actuator, piezomotor, etc. The rotational drive section 282 may be configured as anysuitable drive section such as, for example, a harmonic drive section, adirect drive section, etc. In one aspect the rotational drive section282 shown in FIG. 2E includes one harmonic drive motor 280 for drivingshaft 280S however, in other aspects the drive section may include anysuitable number of harmonic drive motors corresponding to, for example,any suitable number of drive shafts in the coaxial drive system. If thedrive section 282 is a direct drive configuration, no harmonic drive isincluded in the drive section, in this example the rotational drivesection 282 includes a housing 281 that houses the drive motor 280 in amanner substantially similar to that described in U.S. Pat. Nos.6,845,250; 5,899,658; 5,813,823; and 5,720,590, the disclosures of whichare incorporated by reference herein in their entireties. It is notedthat drive shaft 280S may also have a hollow construction (e.g. has ahole running longitudinally along a center of the drive shaft) to allowfor the passage of wires 290 or any other suitable items through thedrive assembly for connection to, for example, another drive section(e.g. such as drive section 201) and/or the at least one robot arm 210,211, 212, 213, mounted to the drive 200.

In another aspect, referring to FIG. 2K, the drive section 282′ may be adirect drive system having one or more degrees of freedom for drivingany suitable drive shafts of the substrate transport robot 104. In oneaspect, the drive section 282′, for example may be a one axis (e.g. onedegree of freedom) drive section or may include any suitable number ofdrive axes. In one aspect, the drive section 282′ generally comprises amotor 244 for driving the drive shaft 280S. As may be realized the drivesystem may not be limited to one motor. The motor 244 comprises a stator248A and a rotor 260A connected to the drive shaft 280S. The stator 248Ais stationarily attached to the housing 281′. The stator 248A generallycomprises an electromagnetic coil. The rotor 260A is comprised ofpermanent magnets, but may alternatively comprise a magnetic inductionrotor that does not have permanent magnets. A sleeve or thin can seal262 is located, if desired, between the rotor 260A and the respectivestator 248A to seal the stator 248A from an operational environment inwhich the at least one robot arm 210, 211, 212, 213 operates. However,the sleeve 262 need not be provided if the transport apparatus robot 104is intended for use in an atmospheric environment. In one aspect, thedrive shaft 280S may be provided with a position sensor 264 (e.g., aposition encoder). The position sensor 264 is used to signal thecontroller 110 of the rotational position of the shaft 280S relative to,e.g., the frame 281′. Any suitable sensor could be used, such as opticalor induction. The drive section 282′ may also include one or moresuitable Z-axis drive 190 to drive at least one robot arm 210, 211, 212,213 in a direction substantially parallel with (e.g. along) the shoulderaxis as a unit.

While the motors are illustrated as rotary motors in other aspects anysuitable motor(s) and/or suitable drive transmission(s) may be used suchas, for example, a direct drive linear motor, linear piezo electricmotors, linear inductance motors, linear synchronous motors, brushed orbrushless linear motors, linear stepper motors, linear servo motors,reluctance motors, etc. Examples of suitable linear motors are describedin, for example, U.S. patent application Ser. No. 13/286,186 entitled“Linear Vacuum Robot with Z Motion and Articulated Arm” filed on Oct.31, 2011; Ser. No. 13/159,034 entitled “Substrate Processing Apparatus”filed on Jun. 13, 2011 and U.S. Pat. No. 7,901,539 entitled “Apparatusand Methods for Transporting and Processing Substrates” issued Mar. 8,2011; U.S. Pat. No. 8,293,066 entitled “Apparatus and Methods forTransporting and Processing Substrates” issued Oct. 23, 2012; U.S. Pat.No. 8,419,341 entitled “Linear Vacuum Robot with Z Motion andArticulated Arm” issued Apr. 16, 2013; U.S. Pat. No. 7,575,406 entitled“Substrate Processing Apparatus” issued Aug. 18, 2009; and U.S. Pat. No.7,959,395 entitled “Substrate Processing Apparatus” issued Jun. 14,2011, the disclosures of which are incorporated herein by reference intheir entireties.

In one aspect the housing 281, 281′ may be mounted to a carriage 270Cwhich is coupled to the Z axis drive 270 such that the Z axis drivemoves the carriage (and the housing 281 located thereon) along the Zaxis. As may be realized, to seal the controlled atmosphere in which theat least one robot arm 210, 211, 212, 213 operates from an interior ofthe drive 200 (which may operate in an atmospheric pressure ATMenvironment) the drive motor 280 may include one or more of theferrofluidic seal 276, 277 and a bellows seal 275. The bellows seal 275may have one end coupled to the carriage 270C and another end coupled toany suitable portion of the frame 200FI so that the interior 200FI ofthe frame 200F is isolated from the controlled atmosphere in which theat least one robot arm 210, 211, 212, 213 operates.

In this aspect the drive shaft 280S may be coupled to the drive section201 for rotating the drive section 201 in the direction of arrow T abouta common axis CAX that may be common to each of the at least one robotarm 210, 211, 212, 213. Here the drive section 201 may include a basemember 250 and at least one drive portion 251, 252. In this aspect thereare two drive portions 251, 252 but in other aspects any suitable numberof drive portions may be provided. The base member 250 includes a framethat forms an interior chamber 250P. Each drive portion 251, 252 alsoincludes a frame 251F, 252F that forms an interior chamber 300P that isin sealed communication with the interior chamber 250P of the basemember 250. As may be realized, each drive portion 251, 252 may includeany suitable access opening that may be sealed by, for example, anysuitable cover 250C. As can be seen in FIG. 2B the base member 250 mayinclude a first and second ends such that a drive portion 251, 252 issealingly coupled to a respective one of the ends. The drive portionsmay be arranged at any suitable angle β (or pitch) relative to oneanother so that an extension/retraction axis of the arm(s) mountedthereon are capable of extending through ports of the transfer chambers125A, 125B, 125C, 125D in which the arm(s) are located. For example, inone aspect the angle β (which may correspond to an angle/pitch betweenthe extension/retraction axes of the drive portions 251, 252) may besubstantially the same as or equal to the angle α of the facets100F1-100F8 of transfer chamber 125A (FIG. 1A). In other aspects theangle β may be about 0° so that the axes of extension/retraction of thedrive portions (and the arm(s) mounted thereon) are substantiallyparallel to one another for extending through the side-by-side ports of,e.g., transfer chambers 125B (FIG. 1B), 125C (FIG. 1C) and 125D (FIG.1D). In still other aspects the angle β may be adjustable (eithermanually or through automation, as will be described below) so that theaxes of extension/retraction of the drive portion 251, 252 may have anysuitable angle β relative to one another. For example, the angle β maybe adjusted between an angle of 0° and θ for extending through ports ofthe transfer chamber 125C (FIG. 1C) and/or for automatic workpiececentering as will be described below. In yet other aspects the angle βand/or spacing (pitch) PT, see FIG. 1C between the drive portions may befixed such that the arms of the substrate transfer robot 104 may extendthrough the ports of the transfer modules having angled facets through arotation of the common drive axes CAX and independent extension oroperation of each drive portion 251, 252. The base member 250 may haveany suitable length L1 so that the axes of extension and retraction R1,R2 of each drive portion 251, 252 are a fixed distance apart where thefixed distance may correspond or otherwise match requirements (e.g. thedistance between ports of a module in which the substrate transfer robot104 is located) imposed by the system tool configuration.

Referring also to FIGS. 3A-3G drive portion 251, 252 will be describedwith respect to drive portion 251. It should be understood that driveportion 252 may be substantially similar to drive portion 251. As notedabove, drive portion 251 includes a frame 251F that may be constructedof a first frame member 251F1 and a second frame member 251F2 that aresealingly coupled to each other in any suitable manner. In other aspectsthe frame may have any suitable configuration and be composed of anysuitable number of frame members. The frame 251F may include an apertureor opening 251M configured for mounting the frame 251F to the basemember 250 in any suitable manner so that an interior chamber 300P ofthe drive portion 251 is in sealed communication with an interiorchamber 250P of the base member 250 so that a common atmosphericenvironment is shared between the interior chambers 250P, 300P and theinterior of housing 281 of drive section 200. In this aspect the driveportion 251 may be configured to support and drive two robot arms 212,213 but in other aspects the drive portion 251 may be configured tosupport and drive any suitable number of robot arms. The drive portion251 may include a first linear rail or slide 310A, 310B (generallylinear rail or slide 310) and a second linear rail or slide 311A, 311B(generally linear rail or slide 311) configured to define a degree offreedom for the independent drive axis that extends and retracts each ofthe respective robot arms 212, 213. In this aspect the drive portionincludes a first drive motor 320 and a second drive motor 321 fordriving a respective arm 212, 213 through, for example, a band andpulley drive transmission.

The first and second drive motors 320, 321 (FIGS. 3D and 3E) may beharmonic or direct drives substantially similar to drive motor 280 whilein other aspects the drive motors 320, 321 may be any suitable drivemotors. Each drive motor 320, 321 may have a respective seal 320S, 321S,such as a ferrofluidic seal for sealing an aperture in the frame 251through which a drive shaft 370 of the motor 320, 321 extends forcoupling, in any suitable manner, to a respective drive pulley 332B,333A. The drive pulley 332B, 333A may be coupled to a respective drivenpulley 332A, 333B in any suitable manner such as by one or more bands.For example, drive pulley 332B may be coupled to driven pulley 332A bybands 330A, 330B. Drive pulley 333A may be coupled to driven pulley 333Bby bands 331A, 333B. The bands 330A, 330B, 331A, 331B may be anysuitable bands such as, for example, those described in, for example,U.S. provisional patent application No. 61/869,870 entitled “SubstrateTransport Apparatus” and filed on Aug. 26, 2013 the disclosure of whichis incorporated herein by reference in its entirety. As may be realized,the drive axes described herein may have any suitable encoders, such asencoders 296, 371 for detecting a position of a respective drive motorand sending one or more signals to any suitable controller such as, forexample, controller 110 for controlling the substrate transfer robot104. As may also be realized, the sealed interior of the drive portions251, 252 and base member 250 allow the drive motors 320, 321 of eachdrive portion 251, 252 to be located in an atmospheric environmentseparated or otherwise sealed from an environment in which the robotarms 210-213 operate. The sealed interior of the drive portions 251, 252and base member 250 also may allow for wire or hose routing from thedrive section 200 to the drive section 201. In such aspects where therobot arms and drive sections are all located in atmosphericenvironment, such as an atmospheric module, as described previously, thedrive interior may not be sealed.

Referring to again to FIGS. 2A-2D and 4A-4B the robot arms 210-213 willbe described with respect to drive portion 252 in accordance withaspects of the disclosed embodiment. In this aspect the robot arms210-213 have a telescoping configuration but in other aspects the robotarms 210-213 may have any suitable configuration. Also in this aspecteach drive portion 251, 252 includes two telescoping arms 210-213 but inother aspects any suitable number of robot arms may be provided on eachdrive portion 251, 252. In this aspect each robot arm 210-213 includes abase member 210B, 211B and an end effector 210E, 211E movably coupled toa respective base member 210B, 211B. Each base member 210B, 211B mayhave an interior in which any suitable transmission may be disposed fordriving the end effector along the axis of extension/retraction. It isnoted that each end effector described herein includes an end effectorseating plane SP (FIG. 2D) in which a substrate is located when beingheld by the end effector. Base member 210B may be movably coupled to thedrive portion 252 through the linear rails 310A, 310B of the so as to bemovable relative to the drive portion 252. Base member 211B may becoupled to the drive portion 252 through the linear rails 311A, 311B soas to be movable relative to the drive portion 252. Each arm 210, 211has a degree of freedom defined by the respective rails such that thedegrees of freedom for each of the robot arms 210 and 211 defined by thelinear rails are parallel to one another (e.g. the transfer plane of theend effectors are located one above the other). As may be realized,robot arms 212, 213 have similar parallel degrees of freedom. As mayalso be realized, the degree of freedom defined by the linear rails forarm 211 may be coplanar with the degree of freedom defined by the linearrails for robot arm 212 (e.g. the end effectors of each robot arm 211,212 are located in the same plane) while the degree of freedom definedby the linear rails for arm 210 may be coplanar with the degree offreedom defined by the linear rails for robot arm 213 (e.g. the endeffectors of each robot arm 210, 213 are located in the same plane).

The base members 210B, 211B may be disposed side-by-side on the driveportion 252 so that base member 210B is coupled to at least one of thebands 330A, 330B so that as the bands 330A, 330B are driven by the motor320 the base member 210B moves with at least one of the bands 330A, 330Bin the direction of extension/retraction R. Base member 211B is coupledto at least one of the bands 331A, 331B so that as the bands 331A, 331Bare driven by the motor 321 the base member 211B moves with at least oneof the bands 331A, 331B in the direction of extension/retraction R. Inother aspects the base members may have any suitable spatial arrangementrelative to each other.

Base member 210B may include a linear rail or slide 410A, 410B disposedat least partly within the interior of the base member to which the endeffector 210E is movably mounted for relative rotation to the basemember 210B and the drive portion 252. Pulleys 410, 411, 420, 421 may berotatably mounted at the ends or at any other suitable location withinthe interior of a respective base member 210B, 211B. One or more bands(similar to those described above), a single continuous loop band/beltor any other suitable transmission member 412, 422 may couple respectiveones of the pulleys 410, 411, 420, 421 to each other. In one aspect eachtransmission member 412, 422 may be grounded to frame 252F of the driveportion 252 so that relative movement between the base member 210B, 211Band the frame 252F drives a respective transmission member 412, 422. Theend effector 211E may be coupled to the transmission member 412 so thatas the base member 211B moves in the direction of arrow R the endeffector also moves in the direction of arrow R relative to the basemember 211B by any suitable drive ratio defined by, for example, thepulleys 410, 411. Similarly, the end effector 210E may be coupled to thetransmission member 412 so that as the base member 210B moves in thedirection of arrow R the end effector also moves in the direction ofarrow R relative to the base member 210B by any suitable drive ratiodefined by, for example, the pulleys 420, 421. As may be realized, abridge member 400 may be provided on one of the end effectors, such asend effectors, 211E, 212E so that the end effector 211E, 212E can bepositioned above the other end effector 210E, 213E of a respective driveportion 251, 252 while allowing the end effectors to pass over/under oneanother.

As noted above, the robot arms described herein are illustrated astelescoping arms (or sliding arms as described below) for exemplarypurposes. However, in other aspects the robot arms may be any suitablerobot arm such as, for a linearly sliding arm 214 as shown in FIG. 2G.In other aspects the arms may be a SCARA arm 215 (FIG. 2H) or othersuitable arm having any suitable arm linkage mechanisms. Suitableexamples of arm linkage mechanisms can be found in, for example, U.S.Pat. No. 7,578,649 issued Aug. 25, 2009, U.S. Pat. No. 5,794,487 issuedAug. 18, 1998, U.S. Pat. No. 7,946,800 issued May 24, 2011, U.S. Pat.No. 6,485,250 issued Nov. 26, 2002, U.S. Pat. No. 7,891,935 issued Feb.22, 2011, U.S. Pat. No. 8,419,341 issued Apr. 16, 2013 and U.S. patentapplication Ser. No. 13/293,717 entitled “Dual Arm Robot” and filed onNov. 10, 2011 and Ser. No. 13/861,693 entitled “Linear Vacuum Robot withZ Motion and Articulated Arm” and filed on Sep. 5, 2013 the disclosuresof which are all incorporated by reference herein in their entireties.In aspects of the disclosed embodiment, the at least one robot arm maybe derived from a conventional SCARA (selective compliant articulatedrobot arm) type design, which includes an upper arm, a band-drivenforearm and a band-constrained end-effector, or from a telescoping armor any other suitable arm design. Suitable examples of robot arms can befound in, for example, U.S. patent application Ser. No. 12/117,415entitled “Substrate Transport Apparatus with Multiple Movable ArmsUtilizing a Mechanical Switch Mechanism” filed on May 8, 2008 and U.S.Pat. No. 7,648,327 issued on Jan. 19, 2010, the disclosures of which areincorporated by reference herein in their entireties. The operation ofthe robot arms may be independent from each other (e.g. theextension/retraction of each arm is independent from other arms), may beoperated through a lost motion switch or may be operably linked in anysuitable way such that the arms share at least one common drive axis. Instill other aspects the transport arms may have any other desiredarrangement such as a frog-leg arm 216 (FIG. 2F) configuration, a leapfrog arm 217 (FIG. 2J) configuration, a bi-symmetric arm 218 (FIG. 21)configuration, etc. Suitable examples of transport arms can be found inU.S. Pat. No. 6,231,297 issued May 15, 2001, U.S. Pat. No. 5,180,276issued Jan. 19, 1993, U.S. Pat. No. 6,464,448 issued Oct. 15, 2002, U.S.Pat. No. 6,224,319 issued May 1, 2001, U.S. Pat. No. 5,447,409 issuedSep. 5, 1995, U.S. Pat. No. 7,578,649 issued Aug. 25, 2009, U.S. Pat.No. 5,794,487 issued Aug. 18, 1998, U.S. Pat. No. 7,946,800 issued May24, 2011, U.S. Pat. No. 6,485,250 issued Nov. 26, 2002, U.S. Pat. No.7,891,935 issued Feb. 22, 2011 and U.S. patent application Ser. No.13/293,717 entitled “Dual Arm Robot” and filed on Nov. 10, 2011 and Ser.No. 13/270,844 entitled “Coaxial Drive Vacuum Robot” and filed on Oct.11, 2011 the disclosures of which are all incorporated by referenceherein in their entireties.

Referring now to FIG. 5, an exemplary substrate transport apparatus 510is illustrated in accordance with aspects of the disclosed embodiment.The substrate transport apparatus 510 is substantially similar to thesubstrate transport apparatus 125A-D described above with respect toFIGS. 2A-4B and may include one or more of the arm configurationsdescribed above. The substrate transport apparatus 510 may be employedin any suitable atmospheric or vacuum environment such as thosedescribed above with respect to the processing apparatus 100A, 100B,100C, 100D. As can be seen in FIG. 5, in one aspect the substratetransport apparatus 510 includes a transport chamber 125B′ and asubstrate transport robot 104A (substantially similar to the substratetransport robot 104 described above) at least partially disposed in thetransport chamber 125B′. The transport chamber 125B′ includes at leastone substrate transport opening 1250P (on at least one side 125S1-S4 ofthe transport chamber 125B′), and at least one robot arm 210A, 211A thathas at least one end effector 210E, 211E disposed at a distal end 210DE,211DE of the robot arm 210A, 211A. Any suitable controller, such ascontroller 110 described above, may be connected to drive section 200′of the substrate transport apparatus 510 and includes a controllermodule 110M having any suitable non-transitory program code foreffecting operation of the substrate transport apparatus 510 asdescribed herein. The at least one robot arm 210A, 211A is shown holdinga substrate S thereon for transporting the substrate S along a transportpath P in radial direction R to, e.g., substrate station module 130(FIG. 1A). As described herein, thermal effects, such as expansion,contraction, twisting, drooping/sagging on the at least one robot arm210A, 211A and other variability in the robot performance (e.g., causedfrom manufacturing variability, wear of robot components, robotcomponent shift, hysteresis, etc.) may be a source of accuracy errorsin, for example, the placement and picking of substrates S from anysuitable substrate including station, such as substrate station module130. The thermal effects and the other variabilities of, for example,the at least one robot arm 210A, 211A may be compensated for, withpositional data provided by or derived from the imaging system 500 toeffect motion compensation for at least substrate S placement in, e.g.,the substrate station module 130 or at any other suitable substrateholding station.

Referring to FIGS. 5-7, as may be realized, the substrate transportrobot 104A is connected to and communicates with the controller 110 sothat the controller 110 may control the movements of the at least onerobot arm 210A, 211A. The controller is configured to command positionalmovement of the substrate transport robot 104A drive axes so that theend effector 210E, 211E is moved to any desired position in theprocessing apparatus 100A, 100B, 100C, 100D (that is within reach of thesubstrate transport apparatus 510) in a known and controlled manner. Forexample the at least one robot arm 210A, 211A may be coupled to thedrive section 200′ which may be any suitable drive section such as thosedescribed previously, and may include any desired position determiningdevices (e.g. such as the position or motor encoders 296, 371; FIGS. 2Eand 3G) that are connected to the controller module 110M of thecontroller 110. The encoders 296, 371 send any suitable signals to thecontroller module 110M enabling the controller module 110M to determinea position of a predetermined point (such as the end effector center orany other suitable location) on the at least one robot arm 210A, 211Arelative to the transport chamber 125B′ (e.g., such as when the at leastone robot arm 210A, 211A is in a retracted position 600).

In one aspect, the controller 110 may be programmed with a predeterminedrepeatable position 650, 650′ of the at least one robot arm 210A, 211Aalong one or more of the R, θ, Z axes, configured to effect motioncompensation without real time input of the drive axis encoder data tofacilitate a decoupling of determination of the motion compensation fromthe encoder data. In one aspect, the controller 110 is configured todetermine when the at least one robot arm 210A, 211A is in thepredetermined repeatable position 650, 650′ based on a known relation toa drive axis datum position. In one aspect, each motor 320′, 321′ 244′(see also motors 320, 321 in FIGS. 3D and 3E) and 280, 244 in FIGS. 2Eand 2K) in the drive section 200′ (e.g., for driving R and θ motion) ordrive axis has a set datum position (which may be referred to as the 0°position) that provides a reference between the motor rotor and themotor stator. The datum position of the motor 320′, 321′, 244′ isfactory set and is substantially constant other than changes Δ_(RV)(FIG. 12) (over time) from motor hysteresis (the Δ_(RV) may be resolved,if desired, from a resolver (such as, e.g., the camera 501R as furtherdescribed below)).

The at least one robot arm 210A, 211A is connected to the drive section200′ (more specifically to the rotor(s) of the respective drive axis)and has (i.e., each arm link/joint has) a corresponding predeterminedrepeatable position 650 (relative to a global reference frame—e.g., thetransport chamber frame 125F′) established by the datum position. Forexample, the datum position may be the at least one robot arm 210A, 211Ain the (fully) retracted position 600 (FIG. 6). The retracted position600 may be known as the top center position in which arm motion is nolonger capable of further retracting (i.e., arm motion is constricted byarm geometry and/or relation of robot arm 210A, 211A and any further armmotion therefrom may be extension of the robot arm 210A, 211A).

In another aspect, the predetermined repeatable position 650′ (FIG. 7)may be selected (or otherwise unconstrained by mechanical geometry)based on an optimal (e.g., time) or desired motion profile of the atleast one robot arm 210A, 211A for transporting the substrate S to anysuitable module, such as substrate station module 130. Here, the atleast one robot arm 210A, 211A is configured so that the at least onerobot arm 210A, 211A retracts no further than a predetermined selectablepoint 650 extended beyond the (fully) retracted position 600 withrespect to transport chamber 125B′ and any further arm motion from thepredetermined selectable point 650 may be extension of the robot arm210A, 211A (i.e., the predetermined repeatable retracted position 650may be offset along R, θ from mechanical constraint of the retractedposition).

Each predetermined repeatable position 650, 650′ (there may be more thanone repeatable retracted position) may be taught to the controller 110along the arm axis of motion R, θ in any suitable manner and has a knownpredetermined relation to the datum position 600. With respect tosubstrate placement correction/compensation, both predeterminedrepeatable positions 650, 650′ are substantially similar with respect tohow they are applied by the controller 110 in motion profile extension.In both aspects, the controller 110 receives a signal that the at leastone robot arm 210A, 211A is in the predetermined repeatable position650, 650′ (either coincident with, or with a known predeterminedrotation, from the datum position). Accordingly, the arm retractionposition (such as positions 650, 650′) is used herein both forconvenience, and a signal of position received by the controller 110communicating with the robot arm 210A, 211A at the predeterminedrepeatable position 650, 650′ is sufficient for position determinationof the robot arm 210A, 211A and for compensation of the arm positionwithout real time input of drive axis encoder data, which may facilitatea decoupling of the determination of position compensation from encoderdata based on known repeatable position signal. In other aspects, driveaxis encoder data may be used for position determination of the robotarm 210A, 211A and positional compensation of the arm 210A, 211A.

Referring now to FIGS. 5, 6, and 8-13, as may be realized and notedabove, dimensional characteristics of the at least one robot arm 210A,211A may vary with environmental conditions, especially temperature. Forexample, the at least one robot arm 210A, 211A may undergo thermalexpansion and contraction (among other thermal effects and/or othervariabilities as noted above) as it is subjected to temperaturevariations during processing. These temperature variations effect thepositioning of the at least one robot arm 210A, 211A, such that acentered position (e.g. a predetermined substrate hold position of theend effector such as reference point 1000WC) of the end effector 210E,211E, or any other suitable portion on the end effector 210E, 211E, suchas point 1010 on the tip of the end effector 210E, 211E (see FIGS. 10and 11)) is offset or has a positional variance Δ_(PV) as furtherdescribed below. In order to correct for positional variances Δ_(PV),the substrate transport apparatus 510 further includes the imagingsystem 500.

The imaging system 500 includes at least one camera 501F, 501R(generally referred to as camera 501) mounted in a predeterminedlocation with respect to the transport chamber 125B′ and disposed so asto image at least part 580 of the robot arm 210A, 211A. The camera 501is configured to image one or more feature(s) of the at least one robotarm 210A, 211A, such as the end effector 210E, 211E or any other part ofthe arm 210A, 211A. The camera 501, which may be internal to or externalfrom the transport chamber 125B′, is mounted so that a field of view FOVof the camera 501 is positioned to capture the desired feature(s) of theat least one robot arm 210A, 211A. For example, the field of view FOVmay be positioned to capture the end effector 210E, 211E with thesubstrate S thereon for determination of a substrate eccentricity Δ_(WC)with respect to the predetermined substrate hold position of the endeffector 210E, 211E. In other aspects, the at least one camera 501 maybe positioned so as to image any suitable portion of the distal end210DE, 211DE (e.g., the end effector 210E, 211E or some feature thereon,the wrist joint, or features thereof joining the end effector 210E, 211Eand arm link at the distal end 210DE, 211DE of the robot arm 210A, 211A)of the robot arm 210A, 211A, or any other suitable feature, such as therear 210R, 211R of the robot arm 210A, 211A.

The camera 501 may be mounted to the transport apparatus 510 in anysuitable manner, such as by mechanical fasteners. The position of thecamera 501 relative to the transport apparatus 510 and system/componentsin the embodiment shown in FIGS. 8 and 9 are merely exemplary, and inalternate embodiments the camera 501 may be mounted in any othersuitable location on the transport apparatus 510. For example, thecamera 501 may be mounted toward the front 125FE (as referenced by thearm end effector direction of motion in extension) of the transportchamber 125B′ (e.g., the front camera 501F) or the rear 125RE of thetransport chamber 125B′ (e.g., the rear camera 501R) to capture thedesired part 580 of the robot arm 210A, 211A as the robot arm 210A, 211Ais extended/retracted or disposed in the predetermined repeatableposition 650, 650′. It is noted that the terms front and rear are usedherein for convenience and any suitable spatial reference terms may beused; further noting that the front and the rear of the transportchamber 125B′ correspond with an extension direction of the robot arm210A, 211A into the process chamber 130 such that the front and reardirections may change depending on a θ orientation of the substratetransport robot 104A relative to the transport chamber 125B′.Additionally, camera 501 is schematically illustrated in FIGS. 8 and 9as two cameras 501F (front), 501R (rear), however camera 501 maycomprise more or less than two cameras (such as four cameras (FIG. 6))distributed at different locations on/in the transport chamber 125B′ soas to image the at least one robot arm 210A, 211A when positioned forpicking and placing substrates S through any of the sides (in thisexample, 4 sides 125S1-S4 are illustrated but in other aspects thetransport chamber 125B′ may have more or less than 4 sides) of thetransport chamber 125B′.

The camera 501 comprises any suitable optics for generating a suitableimage from the field of view FOV of the camera 501. The camera opticsmay include for example, any suitable lenses, filters, mirrors, aperture(not shown) for guiding and controlling the amount of light directed tothe camera 501. The field of view FOV is arranged for the camera 501 toimage a space (i.e., image coverage) that may encompass substantiallythe entire robot arm 210A, 211A and substrate S or any desired partthereof. For example, the camera 501 may be positioned to capture part580 of the at least one robot arm 210A, 211A proximate to the jointcoupling the robot arm 210A, 211A to the drive section (i.e., a shoulderaxis). In one aspect, the camera 501 may be gimbaled by suitableservomotors to rotate the field of view FOV to provide any desired imagecoverage of the robot arm 210A, 211A.

Referring to FIGS. 8-13, the camera 501 is coupled to an imageprocessing module 110IP of the controller 110. The image processingmodule 110IP of the controller 110 may include any suitablenon-transitory program code for operating the camera 501 to captureimages as desired. For example, the image processing module 110IP maysend a generate image command to the camera 501 and instruct the camera501 as to which images are to be transmitted to the controller 110. Theimage processing module 110IP is configured to receive the images fromthe camera 501, and identify a positional variance Δ_(PV) of at leastpart 580 of the robot arm 210A, 211A from the images. In order toidentify the positional variance Δ_(PV), the image processing module110IP includes the calibration image 590 (or other data stored in thecontroller 110 so as to describe dispositive features of the calibrationreal or virtual/design image) of the robot arm 210A, 211A in thepredetermined repeatable position 650, 650′, 600 or any other suitableposition of the robot arm 210A, 211A. The calibration image 590 may begenerated in a number of ways. For example, the calibration image 590may be generated from design information that renders a virtualrepresentation of at least the part 580 of the robot arm 210A, 211Adisposed by design in the camera 501 field of view FOV. In anotheraspect, the calibration image 590 may be generated by the imageprocessing module 110IP of the controller 110 effecting capture of thecalibration image 590, with the camera 501, of the at least part 580 ofthe arm with the arm proximate the predetermined repeatable position650, 650′, 600 or in the predetermined repeatable position 650, 650′,600 or any other suitable position.

As seen in FIGS. 10-13 and 17, there is shown a graphical representationof an exemplary first image 570 of the part 580 of the robot arm 210A(with the arm proximate the predetermined repeatable position 650, 650′,600 or in the predetermined repeatable position 650, 650′, 600 or anyother suitable position) in the field of view FOV of the camera 501overlaid on the calibration image 590 (the calibration image is shown insolid lines while the first image of the part 580 of the robot arm 210Ais shown in dashed lines). For example, the calibration image 590includes an end effector 1000 in the predetermined repeatable position650, 600 before placement into the substrate station modules 130. As maybe realized and shown in FIG. 7, a predetermined repeatable position (ormore than one) 650′ may be located further offset in the direction ofextension (R, θ) from the predetermined repeatable retracted position650, 600 so as to provide a series, or at least a pair (650, 600) ofpredetermined repeatable positions (650′, 600). As may be realized, thefirst image 570 may be generated with the arm a position 600/650. Asecond image from the series is generated with the arm at position650′/650 and so on. The first, second, and each other image in theseries generated with the arm in a different predetermined repeatableposition is compared to, a corresponding calibrated image with the armin the predetermined position. During operation of the at least onerobot arm 210A, 211A in the transport chamber 125B′, and as theprocessing temperature of the substrate processing equipment changes,radial transitions of the robot arm 210A, 211A may drift (e.g., theposition of the imaged end effector and thus point 1010 as well as thecenter point 1000WC that has a fixed relation to point 1010 will varyfrom the position in calibration and as defined in the calibration imageregistered by the controller 110). As such it is possible to measure theresultant thermal effects and/or the other variabilities by comparingthe position data of the calibration image 590 to their relative valuesin at least the first image 570 for the series of predeterminedrepeatable positions 650, 650′, 600. Thus, as may be realized, thoughthe distal end features of the arm vary dimensionally, the predeterminedrepeatable positions 650′, 650, 600 are substantially constant and areregistered by the controller 110 as such (other than motor hysteresisresolved as further described) so that the dimensional variance may bedetermined from leveraging the predetermined repeatable position signalindependent of incremental encoder data.

The first image 570 may depict the reference point (such as point 1010)of the end effector 210E after being placed into the transport chamber125B′ (i.e., retracted or during retraction to the predeterminedrepeatable position 650, 600). The thermal effects and/or othervariabilities can be calculated by comparing the position varianceΔ_(PV) between at least the first image 570 and the calibration image590 (positional variances Δ_(PV) may be performed by suitablealgorithms, resident in controller 110, to identify for example,expansion, contraction, twisting, or drooping/sagging of the at leastone robot arm 210A, 211A; suitable algorithms may be found in, e.g.,U.S. application. Ser. No. 15/209,497, titled “ON THE FLY AUTOMATICWAFER CENTERING METHOD AND APPARATUS” filed Jul. 13, 2016, thedisclosure of which is incorporated herein by reference in itsentirety). For example, in one aspect, the at least one robot arm. 210A,211A picks a substrate S from any suitable substrate holding locationwith the end effector 210E, 211E. The at least one robot arm 210A, 211Amoves into the predetermined repeatable position 650, 650′, 600, forexample, in a (fully) retracted position. 600 (FIG. 17, Block 1601).While in the predetermined repeatable position 650, 650′, the camera 501images and the controller 110 captures at least the first image 570 ofthe part 580 of the at least one robot arm 210A, 211A (FIG. 17, Blocks1602 and 1603). The first image 570 is compared to the calibration image590 (FIG. 17, Block 1604). The position variance Δ_(PV) is determinedbased on comparison of the two images (FIG. 17, Block 1605). As the atleast one robot arm 210A, 211A moves towards the substrate stationmodule 130 (e.g. to place the substrate S), the controller 110 performsmotion compensation based on the determined positional variance Δ_(PV).In other aspects, the controller 110 may be configured to determine acenter 1001WC of the imaged substrate S in at least the first image 570(i.e., a common image operation with the image identifying positionalvariance angles) or with a supplement first image taken with thesubstrate on the end effector and the arm in the predeterminedrepeatable position 650, 650′ and determine a position variance Δ_(WC)from comparison of the determined center 1001WC of the imaged substratewith a predetermined substrate hold position 1000WC in the calibrationimage 590 and adjust a place position of the substrate accordingly. Itis further noted that any suitable number of images may be taken of anysuitable part of the robot arms 210A, 211A and the substrate S and anysuitable number of calibration images may be used to compare theposition variances, such as one calibration image for end effectorpositional variances and one calibration image for substrate centering.

Referring again to FIG. 6, in one aspect, the controller 110 may beconfigured to image, with the imaging system 500, at least a differentfeature on the same arm or a different part 601 (such as the wrist ofthe robot arm 210A, 211A) of the at least one robot arm 210A, 211A (witha predetermined position relative to the at least part 580 of the atleast one robot arm 210A, 211A). For example, as noted above, the frontcamera 501F may be configured to capture at least a second image of,e.g., the joint coupling the end effector to the robot arm 210A, 211A.As may be realized, the controller 110 effects capture of the secondimage of the different part 601 of the at least one robot arm 210A,211A, moving to or in a different predetermined repeatable radialposition such as the position 650′ or other position along the axis ofmotion (R, similar to position 650′, and if desired, with the endeffector located within, wholly or at least in part in the processmodule 130, and may be utilized to calculate another positional varianceΔ_(RV) (FIG. 12) of the at least one robot arm 210A, 211A.

In a further aspect, referring now to FIG. 12, the controller 110 may beconfigured to image, with the imaging system 500, at least differentpart 700 (such as the rear of the robot arm 210A, 211A) of the at leastone robot arm 210A, 211A (with a predetermined position relative to theat least part 580 of the at least one robot arm 210A, 211A). Forexample, as noted above, a resolver (i.e., the rear camera 501R) may beconfigured to capture at least a second image 710 of, e.g., the of thejoint coupling the robot arm 210A, 211A to the drive section 200′ orrear 210R, 211R of the robot arm 210A, 211A (see, e.g., FIGS. 6, 8 and9). As may be realized, the controller 110 effects capture of the secondimage 710 of the different part 700 of the at least one robot arm 210A,211A, moving to or in a different predetermined radial position, and maybe utilized to calculate another positional variance Δ_(RV) (FIG. 12) ofthe at least one robot arm 210A, 211A.

As noted above the position of robot arm 210A, 211A may be affected bydrive axis hysteresis and uncommanded mechanical variances (related tojoint and transmission wear, deformations/reflections, etc.). Thesevariances may be resolved with, e.g., the rear camera 501R (alsoreferred to as a resolver). The rear camera 501R may be positioned suchthat the field of view FOUR captures images of the different part 700 ofthe robot arm 210A, 211A proximate to the location of the joint couplingthe robot arm 210A, 211A (or any desired arm link/joint) to the drivesection 200′ or drive axis (i.e., the rear camera 501R is positioned toimage the rear 210R, 211R of the robot arm 210A, 211A (link)substantially opposite the end effector 210E, 211E, but the camera 201may be positioned as desired. For example, in another aspect, thetransport chamber 125B′ may be a compact transport chamber (with respectto the robot arm 210A, 211A footprint—minimum clearance) and theresolver may be the camera position proximate substantially to thetransport opening 1250P. The camera 501R images the rear 210R, 211R ofthe robot arm 210A, 211A (which may have reference indicia placedthereon as further described below, or may be a structural edge such asof the robot arm 210A in the image) proximate to or at the predeterminedrepeatable position 650, 650′. At least the second image 710 is comparedto a different calibration image 720 (or data including positionalinformation on of a calibrated robot arm 750) to identify the positionalvariance Δ_(RV) from the position of the robot arm 210A, 211A in thesecond image 710 compared to the calibration image 720. In one aspect,the controller 110 may be configured to combine the positional varianceΔ_(RV) determined from the second image 710 with position variance dataΔ_(PV) determined from at least the first image 570 (i.e., from the endof the robot arm 210A, 211A with the end effector 210E, 211E) andteach/update the repeatable retracted and extension position to the armmotion controller module 110M (in other words the data is used to “zero”out the repeatable retract/extension position). In another aspect,Δ_(PV) and Δ_(RV) may be combined for position compensation for pickingand placing substrates.

Referring now to FIG. 13, in one aspect, the first image 570 may includean arm feature 1100 with a predetermined substantially steady statedimension relative to a predetermined substrate hold position (such as1000WC) of the end effector 210E, 211E. Generally, the substantiallysteady state dimension has a dimension component aligned with the radialdirection R and another dimension component in a direction N angled at anon-zero crossing angle α with the radial direction R.

The positional variance calculated by the controller 110 from acomparison of the first image 570 and calibration image 590 of the atleast part 580 of the at least one robot arm 210A, 211A include apositional variance component in the radial direction R and anothervariance component in a direction N angled at the non-zero crossingangle φ with the radial direction R, and the motion compensation factorchanges the extended position of the arm in at least one of the radialdirection and in the angled direction.

Referring now to FIG. 14, in one aspect, the at least part 580 of the atleast one robot arm 210A, 211A captured in the first image 570, includesan indicia pattern 1200 such as a barcode. In one aspect, an incrementaldistribution of indicia 12001 of the indicia pattern 1200 is disposed onthe at least part 580 of the at least one robot arm 210A, 211A. In thisaspect, the controller 110 determines the position variance Δ_(PV), dueto, e.g., thermal changes from comparison of the incrementaldistribution of indicia 12001 imaged in the first image 570 with acalibrated distribution of indicia 1202 in calibration image 1201. Inone aspect, the indicia pattern 1200 has a planar distribution in theradial direction R and a direction M angled at a non-zero crossing angle∨ the radial direction R.

Referring now to FIG. 15, a graph is illustrated showing a waferplacement correction 1400 of wafer placement utilizing the aspects ofthe substrate transport apparatus described herein, compared to waferinitial offset 1401 using conventional methods. Here it can be seenthat, motion compensation provided by the imaging system 500 (comparedto the conventional methods without motion compensation) provides thesubstrate transport apparatus 510 with a placement correction of lessthan or equal to about ±4.5 mm to less than or equal to about ±0.025 mm.For example, the aspects of the present disclosure may provide thesubstrate transport apparatus 510 better accuracy in wafer placementcompared to a conventional substrate apparatus that does not have motioncompensation.

Referring now to FIG. 16, an exemplary operation of the aspects of thedisclosed embodiment will be described. In one aspect, the method 1300includes providing a transport chamber 125B′ of a substrate transportapparatus 510 (FIG. 16, Block 1301). The transport chamber 125B′ havinga substrate transport opening 1250P in communication with a substratestation module 130. The method further includes providing a drivesection 200′ connected to the transport chamber 125B′ (FIG. 16, Block1302), the drive section 200′ having a motor 125M defining at least oneindependent drive axis. The method 1300 further includes providing arobot arm 210A, 211A having end effector 210E, 211E mounted inside thetransport chamber 125B′ (FIG. 16, Block 1303). The robot arm 210A, 211Ais operably connected to the drive section 200′ generating, with the atleast one independent drive axis, at least arm motion in a radialdirection R extending and retracting the robot arm 210A, 211A and movingthe end effector 210E, 211E, in the radial direction R, from a retractedposition to an extended position. While the robot arm 210A, 211A is in apredetermined repeatable position 650, 650′ defined by the at least oneindependent drive axis, imaging system 500 images, with a camera, atleast part of the robot arm 210A, 211A (FIG. 16, Block 1304). Theimaging system 500 is mounted in a predetermined location with respectto the transport chamber 125B′ and the robot arm 210A, 211A is imagedmoving to or in the predetermined repeatable position 650, 650′. Thecontroller 110 captures a first image 570 of at least part 580 of therobot arm 210A, 211A (FIG. 16, Block 1305) on registry of the robot arm210A, 211A proximate to or in the predetermined repeatable position 650,650′ decoupled (i.e., independent) from encoder data of the at least onedrive section 200′. With the first image 570, a positional varianceΔ_(PV) is identified from comparison of the first image 570 with acalibration image 590 (FIG. 16, Block 1306) to determine a motioncompensation factor changing the extended position of the robot arm210A, 211A.

It is noted that although the aspects of the present embodiments aredescribed with respect to the at least one robot arm 210A, 211Aretracting or in a retracted position, the aspects of the presentembodiments may also be used for extension of the robot arm 210A, 211A.For example, the robot arm 210A, 211A may have a repeatable extendedposition that is selected during calibration of the robot arm 210A,211A. The repeatable extended position may be, e.g., at the substratehold position in the processing module 130 which has a knownpredetermined rotation position (θ rotation of the axis drive) from thedrive axis encoder datum. The controller receives a signal from theencoder when the encoder reaches the known predetermined rotationposition to indicate that the robot arm 210A, 211A is in the repeatableextended position. Once in the repeatable extended position, motioncompensation is determined substantially similar to that above withrespect to the robot arm 210A, 211A in the retracted position (i.e., animage is captured and compared with a pre-programmed calibration image).

In accordance with one or more aspects of the disclosed embodiments asubstrate transport apparatus is provided. The substrate transportapparatus including a transport chamber with a substrate transportopening arranged for communication with a substrate station module, adrive section connected to the transport chamber, and having a motordefining at least one independent drive axis, a robot arm mounted insidethe transport chamber, and having an end effector at a distal end of therobot arm, configured to support a substrate thereon, the robot armbeing operably connected to the drive section generating, with the atleast one independent drive axis, at least arm motion in a radialdirection extending and retracting the robot arm and moving the endeffector, in the radial direction, from a retracted position to anextended position, an imaging system with a camera mounted in apredetermined location with respect to the transport chamber anddisposed so as to image at least part of the robot arm, and a controllercommunicably connected to the imaging system and configured to image,with the camera, the at least part of the robot arm moving to or in apredetermined repeatable position defined by the at least oneindependent drive axis, the controller effecting capture of a firstimage of the at least part of the robot arm on registry of the robot armproximate to or in the predetermined repeatable positiondecoupled(independent) from encoder data of the at least one drive axis,wherein the controller is configured to calculate a positional varianceof the at least part of the robot arm from comparison of the first imagewith a calibration image of the at least part of the robot arm, and fromthe positional variance determine a motion compensation factor changingthe extended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments thedetermined motion compensation factor calculated by the controller isindependent of controller registry of the encoder data identifyingposition of the robot arm.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes arobot arm feature, imaged in the first image, with a predeterminedsubstantially steady state dimension relative to a predeterminedsubstrate hold position of the end effector.

In accordance with one or more aspects of the disclosed embodiments thesubstantially steady state dimension has a dimension component alignedwith the radial direction and another dimension component in a directionangled at a non-zero crossing angle with the radial direction.

In accordance with one or more aspects of the disclosed embodiments thepositional variance calculated by the controller from the comparison ofthe first image and calibration image of the at least part of the robotarm include a positional variance component in the radial direction andanother variance component in a direction angled at a non-zero crossingangle with the radial direction, and the motion compensation factorchanges the extended position of the robot arm in at least one of theradial direction and in the angled direction.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes theend effector with a substrate thereon, which end effector with substratebeing imaged in the first image, and the controller determines asubstrate eccentricity with respect to a predetermined substrate holdposition of the end effector.

In accordance with one or more aspects of the disclosed embodiments thecontroller is programmed so as to determine a center of the imagedsubstrate in the first image and determine the position variance fromcomparison of the determined center of the imaged substrate with thepredetermined substrate hold position in the calibration image of the atleast part of the robot arm.

In accordance with one or more aspects of the disclosed embodiments thecontroller determines the position variance due to thermal changes ofthe robot arm from comparison of the robot arm feature imaged in thefirst image with a calibration image of the robot arm feature in thecalibration image of the at least part of the robot arm.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes anindicia pattern with an incremental distribution of indicia on the atleast part of the robot arm, and imaged in the first image, and thecontroller determines the position variance due to thermal changes ofthe robot arm from comparison of the incremental distribution of indiciaimaged in the first image with a calibrated distribution of indicia.

In accordance with one or more aspects of the disclosed embodiments theindicia pattern has a planar distribution in the radial direction and adirection angled at a non-zero crossing angle to the radial direction.

In accordance with one or more aspects of the disclosed embodiments thecalibration image (or data stored in the controller so as to describedispositive features of the calibration image) is generated from designinformation rendering virtual representation of the least part of therobot arm disposed by design in the camera field of view.

In accordance with one or more aspects of the disclosed embodiments thecalibration image is generated by the controller effecting capture ofthe calibration image, with the camera, of the at least part of therobot arm with the arm position proximate or in the predeterminedrepeatable position.

In accordance with one or more aspects of the disclosed embodiments thecontroller is configured to image, with the camera, the at least part ofthe robot arm and/or at least a different part of the robot arm (with apredetermined position relative to the at least part of the robot arm)moving to or in a different predetermined radial position defined by theat least one independent drive axis, the controller effecting capture ofa second image of the at least part of the robot arm and/or at least thedifferent part of the robot arm moving to or in the differentpredetermined radial position, and wherein the controller is configuredto calculate another positional variance of the at least part of therobot arm from comparison of the second image with another calibrationimage of the at least part of the robot arm and/or at least thedifferent part of the robot arm corresponding to the differentpredetermined radial position, and from the other positional variancedetermine a further motion compensation distance combined with themotion compensation distance so as to define a total motion compensationchanging the extended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments thefurther motion compensation distance defines a correction factor to themotion compensation distance to determine the total motion compensationchanging the extended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments asubstrate transport apparatus is provided. The substrate transportapparatus including a transport chamber with a substrate transportopening arranged for communication with a substrate station module, adrive section connected to the transport chamber, and having a motordefining at least one independent drive axis, a robot arm mounted insidethe transport chamber, and having an end effector at a distal end of therobot arm, configured to support a substrate thereon, the robot armbeing operably connected to the drive section generating, with the atleast one independent drive axis, at least arm motion in a radialdirection extending and retracting the robot arm and moving the endeffector, in the radial direction, from a retracted position to anextended position, an imaging system with a camera mounted in apredetermined location with respect to the transport chamber anddisposed so as to image at least part of the robot arm, and a controllercommunicably connected to the imaging system and configured to image,with the camera, the at least part of the robot arm retracting to or ina predetermined repeatable retracted position defined by the at leastone independent drive axis, the controller effecting capture of a firstimage of the at least part of the robot arm on registry of the robot armretraction proximate to or in the predetermined repeatable retractedposition, wherein the controller is configured to identify a positionalvariance of the at least part of the robot arm from comparison of thefirst image with a calibration image of the at least part of the robotarm, and from the positional variance determine a motion compensationdistance changing the extended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments themotion compensation distance calculated by the controller is independentof controller registry of the encoder data identifying position of therobot arm.

In accordance with one or more aspects of the disclosed embodimentscontroller registration of arm position proximity to or in thepredetermined repeatable retracted position is decoupled(independent)from receipt by the controller of encoder data of the at least one driveaxis.

In accordance with one or more aspects of the disclosed embodiments thecontroller is configured to image, with the camera, the at least part ofthe robot arm and/or at least a different part of the robot arm (with apredetermined position relative to the at least part of the robot arm)extending to or in a predetermined extended position defined by the atleast one independent drive axis, the controller effecting capture of asecond image of the at least part of the robot arm and/or at least thedifferent part of the robot arm extending to or in the predeterminedextended position, and wherein the controller is configured to calculateanother positional variance of the at least part of the robot arm fromcomparison of the second image with another calibration image of the atleast part of the robot arm and/or at least the different part of therobot arm, and from the other positional variance determine a furthermotion compensation distance combined with the motion compensationdistance so as to define a total motion compensation changing theextended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments themotion compensation distance and further motion compensation distanceare combined at least as vector component distances to define the totalmotion compensation changing the extended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments amethod is provided. The method including providing a transport chamberof a substrate transport apparatus, the transport chamber having asubstrate transport opening arranged for communication with a substratestation module, providing a drive section connected to the transportchamber, and having a motor defining at least one independent driveaxis, providing a robot arm mounted inside the transport chamber, andhaving an end effector at a distal end of the robot arm, configured tosupport a substrate thereon, the robot arm being operably connected tothe drive section generating, with the at least one independent driveaxis, at least robot arm motion in a radial direction extending andretracting the robot arm and moving the end effector, in the radialdirection, from a retracted position to an extended position, imaging,with a camera of an imaging system mounted in a predetermined locationwith respect to the transport chamber, at least part of the robot armmoving to or in a predetermined repeatable position defined by the atleast one independent drive axis, capturing, with a controllercommunicably connected to the imaging system, a first image of the atleast part of the robot arm on registry of the robot arm proximate to orin the predetermined repeatable position decoupled from encoder data ofthe at least one drive axis, and calculating, with the controller, apositional variance of the at least part of the robot arm fromcomparison of the first image with a calibration image of the at leastpart of the robot arm, and from the positional variance determining amotion compensation factor changing the extended position of the robotarm.

In accordance with one or more aspects of the disclosed embodiments thedetermining the motion compensation factor, calculated by thecontroller, is independent of controller registry of the encoder dataidentifying position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes arobot arm feature, imaged in the first image, with a predeterminedsubstantially steady state dimension relative to a predeterminedsubstrate hold position of the end effector.

In accordance with one or more aspects of the disclosed embodiments thesubstantially steady state dimension has a dimension component alignedwith the radial direction and another dimension component in a directionangled at a non-zero crossing angle with the radial direction.

In accordance with one or more aspects of the disclosed embodimentscalculating the positional variance, with the controller, from thecomparison of the first image and calibration image of the at least partof the robot arm includes comparing a positional variance component inthe radial direction and another variance component in a directionangled at a non-zero crossing angle with the radial direction, and themotion compensation factor changes the extended position of the robotarm in at least one of the radial direction and in the angled direction.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes theend effector with a substrate thereon, which end effector with substratebeing imaged in the first image, the method further includingdetermining, with the controller, a substrate eccentricity with respectto a predetermined substrate hold position of the end effector.

In accordance with one or more aspects of the disclosed embodimentsprogramming the controller so as to determine a center of the imagedsubstrate in the first image and determining, with the controller, theposition variance from comparison of the determined center of the imagedsubstrate with the predetermined substrate hold position in thecalibration image of the at least part of the robot arm.

In accordance with one or more aspects of the disclosed embodimentsdetermining, with the controller, the position variance due to thermalchanges of the robot arm from comparison of the robot arm feature imagedin the first image with a calibration image of the robot arm feature inthe calibration image of the at least part of the robot arm.

In accordance with one or more aspects of the disclosed embodiments theat least part of the robot arm captured in the first image includes anindicia pattern with an incremental distribution of indicia on the atleast part of the robot arm, and imaged in the first image, the methodfurther including determining, with the controller, the positionvariance due to thermal changes of the robot arm from comparison of theincremental distribution of indicia imaged in the first image with acalibrated distribution of indicia.

In accordance with one or more aspects of the disclosed embodiments theindicia pattern has a planar distribution in the radial direction and adirection angled at a non-zero crossing angle to the radial direction.

In accordance with one or more aspects of the disclosed embodimentsgenerating the calibration image from design information renderingvirtual representation of the least part of the robot arm disposed bydesign in the camera field of view.

In accordance with one or more aspects of the disclosed embodimentsgenerating the calibration image, with the controller, by effectingcapture of the calibration image, with the camera, of the at least partof the robot arm with the arm position proximate or in the predeterminedrepeatable position.

In accordance with one or more aspects of the disclosed embodimentsimaging, with the camera, the at least part of the robot arm and/or atleast a different part of the robot arm moving to or in a differentpredetermined radial position defined by the at least one independentdrive axis, effecting capture, with the controller, of a second image ofthe at least part of the robot arm and/or at least the different part ofthe robot arm moving to or in the different predetermined radialposition, calculating, with the controller, another positional varianceof the at least part of the robot arm from comparison of the secondimage with another calibration image of the at least part of the robotarm and/or at least the different part of the robot arm corresponding tothe different predetermined radial position, and determining a furthermotion compensation distance combined with the motion compensationdistance so as to define a total motion compensation changing theextended position of the robot arm.

In accordance with one or more aspects of the disclosed embodiments thefurther motion compensation distance defines a correction factor to themotion compensation distance to determine the total motion compensationchanging the extended position of the robot arm.

What is claimed is:
 1. A substrate transport apparatus comprising: atransport chamber with a substrate transport opening arranged forcommunication with a substrate station module; a drive section connectedto the transport chamber, and having a motor defining at least oneindependent drive axis; a robot arm mounted inside the transportchamber, and having an end effector at a distal end of the robot arm,configured to support a substrate thereon, the robot arm being operablyconnected to the drive section generating, with the at least oneindependent drive axis, at least arm motion in a radial directionextending and retracting the robot arm and moving the end effector, inthe radial direction, from a retracted position to an extended position;an imaging system with a camera mounted in a predetermined location withrespect to the transport chamber and disposed so as to image at leastpart of the robot arm; and a controller communicably connected to theimaging system and configured to image, with the camera, the at leastpart of the robot arm moving to or in a predetermined repeatableposition defined by the at least one independent drive axis, thecontroller effecting capture of a first image of the at least part ofthe robot arm on registry of the robot arm proximate to or in thepredetermined repeatable position decoupled from encoder data of the atleast one drive axis, wherein the controller is configured to calculatea positional variance of the at least part of the robot arm fromcomparison of the first image with a calibration image of the at leastpart of the robot arm, and from the positional variance determine amotion compensation factor changing the extended position of the robotarm.
 2. The substrate transport apparatus of claim 1, wherein thedetermined motion compensation factor calculated by the controller isindependent of controller registry of the encoder data identifyingposition of the robot arm.
 3. The substrate transport apparatus of claim1, wherein the positional variance calculated by the controller from thecomparison of the first image and calibration image of the at least partof the robot arm include a positional variance component in the radialdirection and another variance component in a direction angled at anon-zero crossing angle with the radial direction, and the motioncompensation factor changes the extended position of the robot arm in atleast one of the radial direction and in the angled direction.
 4. Thesubstrate transport apparatus of claim 1, wherein the at least part ofthe robot arm captured in the first image includes the end effector witha substrate thereon, which end effector with substrate being imaged inthe first image, and the controller determines a substrate eccentricitywith respect to a predetermined substrate hold position of the endeffector.
 5. The substrate transport apparatus of claim 4, wherein thecontroller is programmed so as to determine a center of the imagedsubstrate in the first image and determine the position variance fromcomparison of the determined center of the imaged substrate with thepredetermined substrate hold position in the calibration image of the atleast part of the robot arm.
 6. The substrate transport apparatus ofclaim 1, wherein the at least part of the robot arm captured in thefirst image includes an robot arm feature, imaged in the first image,with a predetermined substantially steady state dimension relative to apredetermined substrate hold position of the end effector.
 7. Thesubstrate transport apparatus of claim 6, wherein the substantiallysteady state dimension has a dimension component aligned with the radialdirection and another dimension component in a direction angled at anon-zero crossing angle with the radial direction.
 8. The substratetransport apparatus of claim 6, wherein the controller determines theposition variance due to thermal changes of the robot arm fromcomparison of the robot arm feature imaged in the first image with acalibration image of the robot arm feature in the calibration image ofthe at least part of the robot arm.
 9. The substrate transport apparatusof claim 6, wherein the at least part of the robot arm captured in thefirst image includes an indicia pattern with an incremental distributionof indicia on the at least part of the robot arm, and imaged in thefirst image, and the controller determines the position variance due tothermal changes of the robot arm from comparison of the incrementaldistribution of indicia imaged in the first image with a calibrateddistribution of indicia.
 10. The substrate transport apparatus of claim9, wherein the indicia pattern has a planar distribution in the radialdirection and a direction angled at a non-zero crossing angle to theradial direction.
 11. The substrate transport apparatus of claim 1,wherein the calibration image is generated from design informationrendering virtual representation of the least part of the robot armdisposed by design in a camera field of view.
 12. The substratetransport apparatus of claim 1, wherein the calibration image isgenerated by the controller effecting capture of the calibration image,with the camera, of the at least part of the robot arm with the armposition proximate or in the predetermined repeatable position.
 13. Thesubstrate transport apparatus of claim 1, wherein the controller isconfigured to image, with the camera, the at least part of the robot armand/or at least a different part of the robot arm moving to or in adifferent predetermined radial position defined by the at least oneindependent drive axis, the controller effecting capture of a secondimage of the at least part of the robot arm and/or at least thedifferent part of the robot arm moving to or in the differentpredetermined radial position, and wherein the controller is configuredto calculate another positional variance of the at least part of therobot arm from comparison of the second image with another calibrationimage of the at least part of the robot arm and/or at least thedifferent part of the robot arm corresponding to the differentpredetermined radial position, and from the other positional variancedetermine a further motion compensation distance combined with themotion compensation distance so as to define a total motion compensationchanging the extended position of the robot arm.
 14. The substratetransport apparatus of claim 13, wherein the further motion compensationdistance defines a correction factor to the motion compensation distanceto determine the total motion compensation changing the extendedposition of the robot arm.
 15. A substrate transport apparatuscomprising: a transport chamber with a substrate transport openingarranged for communication with a substrate station module; a drivesection connected to the transport chamber, and having a motor definingat least one independent drive axis; a robot arm mounted inside thetransport chamber, and having an end effector at a distal end of therobot arm, configured to support a substrate thereon, the robot armbeing operably connected to the drive section generating, with the atleast one independent drive axis, at least arm motion in a radialdirection extending and retracting the robot arm and moving the endeffector, in the radial direction, from a retracted position to anextended position; an imaging system with a camera mounted in apredetermined location with respect to the transport chamber anddisposed so as to image at least part of the robot arm; and a controllercommunicably connected to the imaging system and configured to image,with the camera, the at least part of the robot arm retracting to or ina predetermined repeatable retracted position defined by the at leastone independent drive axis, the controller effecting capture of a firstimage of the at least part of the robot arm on registry of the robot armretraction proximate to or in the predetermined repeatable retractedposition, wherein the controller is configured to identify a positionalvariance of the at least part of the robot arm from comparison of thefirst image with a calibration image of the at least part of the robotarm, and from the positional variance determine a motion compensationdistance changing the extended position of the robot arm.
 16. Thesubstrate transport apparatus of claim 15, wherein the motioncompensation distance calculated by the controller is independent ofcontroller registry of the encoder data identifying position of therobot arm.
 17. The substrate transport apparatus of claim 15, whereincontroller registration of arm position proximity to or in thepredetermined repeatable retracted position is decoupled from receipt bythe controller of encoder data of the at least one drive axis.
 18. Thesubstrate transport apparatus of claim 15, wherein the controller isconfigured to image, with the camera, the at least part of the robot armand/or at least a different part of the robot arm extending to or in apredetermined extended position defined by the at least one independentdrive axis, the controller effecting capture of a second image of the atleast part of the robot arm and/or at least the different part of therobot arm extending to or in the predetermined extended position, andwherein the controller is configured to calculate another positionalvariance of the at least part of the robot arm from comparison of thesecond image with another calibration image of the at least part of therobot arm and/or at least the different part of the robot arm, and fromthe other positional variance determine a further motion compensationdistance combined with the motion compensation distance so as to definea total motion compensation changing the extended position of the robotarm.
 19. The substrate transport apparatus of claim 18, wherein themotion compensation distance and further motion compensation distanceare combined at least as vector component distances to define the totalmotion compensation changing the extended position of the robot arm. 20.A method comprising: providing a transport chamber of a substratetransport apparatus, the transport chamber having a substrate transportopening arranged for communication with a substrate station module;providing a drive section connected to the transport chamber, and havinga motor defining at least one independent drive axis; providing a robotarm mounted inside the transport chamber, and having an end effector ata distal end of the robot arm, configured to support a substratethereon, the robot arm being operably connected to the drive section;generating, with the at least one independent drive axis, at least robotarm motion in a radial direction extending and retracting the robot armand moving the end effector, in the radial direction, from a retractedposition to an extended position; imaging, with a camera of an imagingsystem mounted in a predetermined location with respect to the transportchamber, at least part of the robot arm moving to or in a predeterminedrepeatable position defined by the at least one independent drive axis;capturing, with a controller communicably connected to the imagingsystem, a first image of the at least part of the robot arm on registryof the robot arm proximate to or in the predetermined repeatableposition decoupled from encoder data of the at least one drive axis; andcalculating, with the controller, a positional variance of the at leastpart of the robot arm from comparison of the first image with acalibration image of the at least part of the robot arm, and from thepositional variance determining a motion compensation factor changingthe extended position of the robot arm.
 21. The method of claim 20,wherein the determining the motion compensation factor, calculated bythe controller, is independent of controller registry of the encoderdata identifying position of the robot arm.
 22. The method of claim 20,further comprising calculating the positional variance, with thecontroller, from the comparison of the first image and calibration imageof the at least part of the robot arm includes comparing a positionalvariance component in the radial direction and another variancecomponent in a direction angled at a non-zero crossing angle with theradial direction, and the motion compensation factor changes theextended position of the robot arm in at least one of the radialdirection and in the angled direction.
 23. The method of claim 20,wherein the at least part of the robot arm captured in the first imageincludes the end effector with a substrate thereon, which end effectorwith substrate being imaged in the first image, the method furthercomprising determining, with the controller, a substrate eccentricitywith respect to a predetermined substrate hold position of the endeffector.
 24. The method of claim 23, further comprising programming thecontroller so as to determine a center of the imaged substrate in thefirst image and determining, with the controller, the position variancefrom comparison of the determined center of the imaged substrate withthe predetermined substrate hold position in the calibration image ofthe at least part of the robot arm.
 25. The method of claim 20, whereinthe at least part of the robot arm captured in the first image includesan robot arm feature, imaged in the first image, with a predeterminedsubstantially steady state dimension relative to a predeterminedsubstrate hold position of the end effector.
 26. The method of claim 25,further comprising the substantially steady state dimension has adimension component aligned with the radial direction and anotherdimension component in a direction angled at a non-zero crossing anglewith the radial direction.
 27. The method of claim 25, furthercomprising determining, with the controller, the position variance dueto thermal changes of the robot arm from comparison of the robot armfeature imaged in the first image with a calibration image of the robotarm feature in the calibration image of the at least part of the robotarm.
 28. The method of claim 25, wherein the at least part of the robotarm captured in the first image includes an indicia pattern with anincremental distribution of indicia on the at least part of the robotarm, and imaged in the first image, the method further comprisingdetermining, with the controller, the position variance due to thermalchanges of the robot arm from comparison of the incremental distributionof indicia imaged in the first image with a calibrated distribution ofindicia.
 29. The method of claim 28, wherein the indicia pattern has aplanar distribution in the radial direction and a direction angled at anon-zero crossing angle to the radial direction.
 30. The method of claim20, further comprising generating the calibration image from designinformation rendering virtual representation of the least part of therobot arm disposed by design in a camera field of view.
 31. The methodof claim 20, further comprising generating the calibration image, withthe controller, by effecting capture of the calibration image, with thecamera, of the at least part of the robot arm with the arm positionproximate or in the predetermined repeatable position.
 32. The method ofclaim 20, further comprising imaging, with the camera, the at least partof the robot arm and/or at least a different part of the robot armmoving to or in a different predetermined radial position defined by theat least one independent drive axis, effecting capture, with thecontroller, of a second image of the at least part of the robot armand/or at least the different part of the robot arm moving to or in thedifferent predetermined radial position; and calculating, with thecontroller, another positional variance of the at least part of therobot arm from comparison of the second image with another calibrationimage of the at least part of the robot arm and/or at least thedifferent part of the robot arm corresponding to the differentpredetermined radial position, and determining a further motioncompensation distance combined with the motion compensation distance soas to define a total motion compensation changing the extended positionof the robot arm.
 33. The method of claim 32, wherein the further motioncompensation distance defines a correction factor to the motioncompensation distance to determine the total motion compensationchanging the extended position of the robot arm.